PARTICULATE ORGANIC MATTER I N SEA WATER
55
levelled off without showing a definite peak. Hence the experiments
as a whole show a large variation in maximum concentration.
In an attempt t o find out whether bacteria are essential to this
process, some of the experiments have been poisoned with potassium
dichromate (1 mg/litre) or potassium cyanide (50 mg/litre). No peaks
were observed in these experiments, but there was some slight increase
“ O i
P
b
1 0
20
30
TIME IN DAYS
FIG. 6 . In situ formation of particulate organic matter. Samples were filtered and
allowed t o stand, with no further treatment.
to a “ steady state ” at a lower level than would be expected when
bacteria are allowed to grow freely. However, the results were equivocal, for bacteria were not completely eliminated, particularly in the
case of dichromate treatment.
TABLE 11. AVERAGE CONCENTRATION OF PARTICULATE ORGANIC CARBON
(MG C/LITRE) OBTAINED IN STUDIES OF BACTERIAL EFFECTS ON BUBBLED
WATER AND in situ PRODUCTION AND UTILIZATION
Maximum
Steady State
Bubbled ; bacteria added
0.44 & 0.25
0.20 f 0.06
In aitu, with or without bacterial inoculation
0.15 f 0.08
0.41 f 0.30
In situ, poisoned
-
0.10 * 0.02
_____
~ _ _ _ _ _
~ ~ _ _ _ _
Table I1 summarizes the results of fifteen experiments with inshore
waters taken near the Nova Scotia coast, showing maximum observed
concentrations averaged for each type of experiment and the “ steady
state ” concentration attained after the peak.